endosümbiootilisest

Endosümbiootilisest refers to a symbiotic relationship where one organism lives inside another organism. This internal dwelling is typically within the cells of the host organism, though it can also occur within intercellular spaces. The relationship is mutualistic, meaning both organisms benefit, or it can be commensalistic, where one benefits and the other is neither harmed nor helped. A classic and well-supported example of endosymbiosis is the theory of endosymbiotic origin for mitochondria and chloroplasts within eukaryotic cells. This theory posits that these organelles were once free-living prokaryotes that were engulfed by a larger host cell, and instead of being digested, they established a beneficial relationship. Over time, these engulfed organisms evolved into the mitochondria responsible for cellular respiration and the chloroplasts responsible for photosynthesis. This endosymbiotic event is considered a pivotal moment in the evolution of complex life on Earth, enabling the development of multicellular organisms with sophisticated energy-generating capabilities. The evidence for this theory includes the presence of their own circular DNA, similar to bacterial DNA, and their double-membrane structure, with the inner membrane resembling that of prokaryotes.